Inclined detonation engine suitable for supersonic wide-range operation condition

Abstract

The invention discloses an oblique detonation engine suitable for supersonic wide-range operation conditions, the lower surface of a combustion chamber of the oblique detonation engine is arranged to be a wedge surface, the wedge surface of the combustion chamber adopts a curved surface structure design in the direction perpendicular to the flowing direction, so that the angle of the wedge surface continuously changes in the direction perpendicular to the incoming flow direction of an inlet of the combustion chamber. According to the oblique detonation engine provided by the invention, through the structural design of the three-dimensional curved wedge surface combustion chamber, wedge surfaces with continuously changed angles are formed at different positions perpendicular to the incoming flow direction in the combustion chamber, and different positions have different detonation angles, so that quick triggering of local detonation points is realized; and formation and development of oblique detonation waves in the whole combustion chamber are accelerated. Through the design of the combustion chamber of the three-dimensional curved wedge surface structure, the stable operation working condition range of the combustion chamber of the supersonic propulsion system based on oblique detonation combustion under the wide-area flight condition is widened, the through-flow area of the combustion chamber is increased while rapid and stable ignition is guaranteed, and the flow pressure loss in the combustion chamber is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of supersonic aircraft design, in particular to an oblique detonation engine suitable for supersonic wide-range operating conditions. Background Art

[0002] The oblique detonation propulsion system (ODE) based on oblique detonation combustion has received increasing attention in the aerospace field due to its fast heat release rate, high thermal cycle efficiency and wide operating range. Its feasibility and superiority have been confirmed in early studies. It is suitable for air-breathing supersonic aircraft with higher flight Mach numbers than scramjet engines.

[0003] Different from traditional combustion, oblique detonation combustion is based on strong shock wave compression to achieve self-ignition, and can achieve rapid conversion of chemical energy into thermal energy at the millimeter scale. Therefore, the oblique detonation propulsion system has engineering application advantages such as simple and compact structure and superior high-speed flight performance, and is a research hotspot and development trend in the field of aerospace propulsion. However, the initiation and stationary conditions of oblique detonation are extremely harsh, and the stable operating conditions are significantly affected by the flight state. Therefore, it is a very challenging task to achieve flexible and smooth startup and stable power output of the oblique detonation propulsion system.

[0004] There are many factors that affect the stationary of oblique detonation waves, such as: the equivalence ratio of the incoming premixed combustible gas, the incoming temperature and pressure, the incoming Mach number and the wedge angle. For a given wedge angle, when the Mach number of the combustion chamber inflow changes within a certain range, the oblique detonation can be stationary, and the detonation time and detonation distance also change accordingly. Currently, the existing oblique detonation combustion chambers mostly use a straight wedge structure, or accelerate the detonation by setting a protrusion and other structures along the incoming flow direction, which increases the flow loss to a certain extent. In addition, the wedge surface of the structure does not change along the width direction of the combustion chamber, which makes the angle range of the successful detonation of the oblique detonation in the combustion chamber smaller. Therefore, the oblique detonation stationary Mach number range applicable to this type of structure is smaller.

[0005] The size of the oblique detonation stationary range reflects the difficulty of stable combustion of the oblique detonation wave, which is directly related to factors such as the incoming flow conditions and the combustion chamber structure. Among them, for oblique detonation engines under wide-range flight conditions, the design of the wedge surface structure in the combustion chamber directly determines the initiation efficiency and stationary range of the oblique detonation. Summary of the invention

[0006] In view of this, an object of the present invention is to provide an oblique detonation engine and a design method suitable for supersonic wide-range operating conditions. The oblique detonation engine achieves wide-range stable flight at supersonic speeds through a three-dimensional curved wedge surface structure of the combustion chamber.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides an oblique detonation engine suitable for supersonic wide-range operating conditions, wherein the lower surface of the combustion chamber of the oblique detonation engine is arranged as a wedge surface, and the wedge surface of the combustion chamber adopts a curved surface structure design in a direction perpendicular to the flow direction, so that the angle of the wedge surface changes continuously in a direction perpendicular to the flow direction at the combustion chamber inlet.

[0009] Furthermore, the front edge of the wedge surface of the combustion chamber is in the shape of a straight line, and the rear edge of the wedge surface is in the shape of a curve.

[0010] Furthermore, the curved surface is a variable wedge angle curved surface.

[0011] Furthermore, the curved surface takes a cross section perpendicular to the air intake direction, and the contour shape of the cross section is a combination of several smooth curves.

[0012] Furthermore, the variable wedge angle curved surface adopts an n-shaped or / and U-shaped curved surface.

[0013] Furthermore, the wedge angles at different positions in the combustion chamber perpendicular to the incoming flow direction are (θ 1 ,θ 2 ) changes continuously between 1 The value range is 15-30 degrees, θ 2 The value range is 20-40 degrees; among them, θ 1 θ is the minimum wedge angle corresponding to the maximum position between the wedge surface in the combustion chamber and the upper surface of the combustion chamber; 2 It is the maximum wedge angle corresponding to the minimum position between the wedge surface in the combustion chamber and the upper surface of the combustion chamber.

[0014] Furthermore, the angle change (θ 1 ,θ 2 ) in the stationary range (θ det,CJ ,θ det,max ), where θ det,CJ is the wedge angle corresponding to the Chapman-Jouguet oblique detonation; θ det,max It is the maximum wedge angle corresponding to the condition that the oblique detonation wave does not detach from the body.

[0015] Furthermore, the wedge angle formed by the curved surface varies in the range of 0-15 degrees.

[0016] Furthermore, the angle of the oblique detonation wave generated by the combustion chamber varies from 0 to 20 degrees in a direction perpendicular to the wedge surface.

[0017] Furthermore, the Mach number of the inlet flow of the combustion chamber is between 3 and 15.

[0018] The beneficial effects of the present invention are:

[0019] The oblique detonation engine provided by the present invention is suitable for supersonic wide-range operation conditions, wherein the lower surface of the combustion chamber of the oblique detonation engine is set as a wedge surface, and the wedge surface of the combustion chamber adopts a curved surface structure design in the direction perpendicular to the flow, so that the angle of the wedge surface changes continuously in the direction perpendicular to the flow from the combustion chamber inlet. The oblique detonation engine provided by the present invention forms wedge surfaces with continuously changing angles at different positions of the combustion chamber perpendicular to the flow direction through the structural design of the three-dimensional curved wedge surface combustion chamber, and different positions have different detonation angles, thereby realizing the rapid triggering of the local explosion point and accelerating the formation and development of the oblique detonation wave in the entire combustion chamber.

[0020] The combustion chamber design with an N-shaped or / and U-shaped three-dimensional curved wedge structure is adapted to the variable incoming flow state under different engine operating conditions, thereby improving the stable operating condition range and propulsion performance of the combustion chamber of a supersonic propulsion system based on oblique detonation combustion under wide-range flight conditions. While ensuring rapid and stable ignition, the flow area of ​​the combustion chamber is increased, and the flow pressure loss in the combustion chamber is reduced, ultimately achieving rapid ignition and wide-range efficient flight of the oblique detonation engine at supersonic speed.

[0021] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for explanation.

[0023] Figure 1 It is a schematic diagram of an air-breathing supersonic propulsion system based on oblique detonation combustion and a partial enlarged schematic diagram of the combustion chamber.

[0024] Figure 2 is the oblique detonation angle (β det ) and the oblique shock angle (β sho ) as the wedge angle (θ) changes.

[0025] Figure 3 It is a three-dimensional cross-sectional schematic diagram of an engine combustion chamber structure with an n-shaped wedge surface design.

[0026] Figure 4 It is a plan view of an engine combustion chamber with an n-shaped wedge surface design added.

[0027] Figure 5 It is a plan view of an engine combustion chamber with an added U-shaped wedge surface design.

[0028] Figure 6 It is a plan view of an engine combustion chamber with an n and U combined wedge surface design.

[0029] Explanation of the reference numerals: 1 represents the engine air intake; 2 represents the engine body; 3 represents the engine combustion chamber; 4 represents the curved wedge surface; 5 represents the engine tail nozzle; θ 1 Indicates the minimum wedge angle of the combustion chamber wedge surface; θ 2 Indicates the maximum wedge angle of the combustion chamber wedge surface. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0031] like Figure 1 As shown, the oblique detonation engine suitable for supersonic wide-range operating conditions provided in this embodiment includes a body, and the body includes a forebody, a combustion chamber, and a nozzle. The lower surface of the combustion chamber of the oblique detonation engine is set as a wedge surface, and the wedge surface of the combustion chamber adopts a curved surface structure design perpendicular to the flow direction, so that the angle of the wedge surface changes continuously in the direction perpendicular to the flow direction at the combustion chamber inlet, thereby increasing the detonation efficiency of the oblique detonation, expanding the stable combustion range of the oblique detonation, improving the combustion efficiency of the supersonic propulsion system, and realizing wide-range stable flight at supersonic speed.

[0032] The angle of the wedge surface in this embodiment is the angle between the direction of the incoming gas in front of the combustion chamber and the wedge surface; the front edge of the wedge in the combustion chamber in this embodiment is a straight line, and the rear edge of the wedge surface is a curve; the curved surface in this embodiment is a variable wedge angle curved surface, and the variable wedge angle curved surface adopts an n-type or / and U-type curved surface.

[0033] The curved surface is a cross-section of the wedge surface along the air intake direction, and its cross-sectional profile shape is a smooth curve of different shapes or a combination thereof; the smooth curve includes an arc shape, an ellipse or a parabola, etc.; the wedge surface angle formed by the curved surface cross-section in this embodiment varies in the range of 0-15 degrees, and the optimal range is 5-15 degrees; the angle of the oblique detonation wave in this embodiment varies in the angle perpendicular to the wedge surface direction from 0 to 20 degrees, and the optimal range is 5-10 degrees.

[0034] In this embodiment, the cross-sectional shape of the wedge surface and the angle variation range of the wedge surface can be adjusted to achieve a stable combustion range of controlling the oblique detonation in the combustion chamber.

[0035] The Mach number of the inlet flow of the combustion chamber described in this embodiment is between 3-15.

[0036] The oblique detonation combustion chamber provided in this embodiment is suitable for supersonic wide-range operating conditions, can achieve stable and rapid ignition of the oblique detonation combustion chamber, and improve the stability and reliability of combustion in the engine combustion chamber over a wider Mach number range, so as to ensure stable and efficient output of aircraft power.

[0037] In this embodiment, the initiation and stationary range of the oblique detonation wave is controlled by a combustion chamber with a variable wedge angle curved surface. This structure can be applied to an air-breathing supersonic propulsion system based on oblique detonation combustion. The combustion chamber uses wedge surfaces with continuously changing angles at different positions perpendicular to the incoming flow direction, so that different positions of the wedge surface of the combustion chamber have different initiation angles. By quickly triggering the local detonation point, the formation and development of the detonation in the entire combustion chamber are accelerated and induced to adapt to the variable incoming flow state under different operating conditions of the engine, and finally the rapid initiation and stable stationary of the oblique detonation in the combustion chamber of the supersonic propulsion system under a wide range of operating conditions are achieved.

[0038] This embodiment describes in detail the working principle of the oblique detonation engine applicable to supersonic wide-range operation conditions in conjunction with the accompanying drawings:

[0039] like Figure 1 As shown, the two appendage shock waves induced by the supersonic flow through the forebody are compressed and mixed with the fuel injected into the front end of the fuselage. The mixed gas flows into the combustion chamber through the fairing, and an oblique detonation is formed under the induction of the wedge surface in the combustion chamber. The detonation combustion products are ejected through the nozzle to generate thrust, providing power for the air-breathing supersonic aircraft.

[0040] like Figure 2 As shown, Figure 2 is the oblique detonation angle (β det ) and the oblique shock angle (β sho ) with the wedge angle (θ), the solid line in the figure indicates the angle range in which the oblique detonation and oblique shock waves can be stably stationed. As the wedge angle (θ) increases, the angles of the oblique detonation and oblique shock waves that can be formed increase. For a given incoming flow condition, the stationing range of the oblique detonation and oblique shock waves is shown by the solid line in the figure, which is reflected in the changes in the wedge angle (θ) and is det,CJ ,θ det,max ) and (0,θ sho,max ), also known as the stationary range.

[0041] In this embodiment, the oblique detonation angle β det It refers to the angle between the oblique detonation wave and the direction of the incoming gas flow in the combustion chamber during the oblique detonation combustion process;

[0042] In this embodiment, the wedge surface angle θ refers to the angle between the direction of the incoming gas flow in front of the combustion chamber in the detonation engine and the wedge surface;

[0043] In this embodiment, θ det,CJis the wedge angle corresponding to the Chapman-Jouguet oblique detonation;

[0044] In this embodiment, θ det,max is the maximum wedge angle corresponding to the condition that the oblique detonation wave does not detach from the body;

[0045] In this embodiment, θ sho,max is the maximum wedge angle corresponding to the condition that the oblique shock wave does not detach from the body;

[0046] In this embodiment, β det,CJ is the oblique detonation angle corresponding to the occurrence of Chapman-Jouguet oblique detonation;

[0047] In this embodiment, β det,max It is the maximum oblique detonation angle that can be maintained without the oblique detonation wave separating from the body;

[0048] In this embodiment, β sho,max is the maximum oblique shock wave angle that can be maintained without the oblique shock wave detaching from the body;

[0049] In this embodiment, n It represents the normal Mach number behind the oblique detonation wave.

[0050] Combination Figure 3-4 In the embodiment shown, by setting n-shaped (such as Figure 4 The distance between the middle of the n-shaped wedge surface and the upper surface of the combustion chamber is smaller than the distance between the two sides of the edge and the upper surface of the combustion chamber; so that the wedge angles at different positions in the combustion chamber perpendicular to the incoming flow direction are (θ 1 ,θ 2 ) and can change continuously between wedge angles θ 2 The nearby wedge surface realizes the rapid triggering of the local explosion point, accelerates the formation and development of the oblique detonation wave in the entire combustion chamber, and the wedge surface at a smaller angle position increases the flow area of ​​the combustion chamber, which is beneficial to reducing the flow loss in the combustion chamber.

[0051] Among them, θ 1 θ is the minimum wedge angle corresponding to the maximum distance between the edges of the n-shaped wedge surface in the combustion chamber and the upper surface of the combustion chamber; 2 θ is the maximum wedge angle corresponding to the position where the distance between the middle of the n-shaped wedge surface in the combustion chamber and the upper surface of the combustion chamber is the minimum; 1 The value range of θ is 15-30 degrees; 2 The value range is 20-40 degrees.

[0052] Combination Figure 5 In the embodiment shown, the combustion chamber is arranged in a U shape (such as Figure 5 Section BB shows the wedge surface, and the rest of the structure is the same as Figure 4The same working principle as Figure 4 The distance between the middle of the U-shaped wedge surface and the upper surface of the combustion chamber is greater than the distance between the two sides of the edge and the upper surface of the combustion chamber.

[0053] Combination Figure 6 In the embodiment shown, the combustion chamber is arranged in a U-shaped or n-shaped combination (such as Figure 5 Section BB shows the wedge surface, and the rest of the structure is the same as Figure 4 Similarly, for a combustion chamber with a larger width, this setting can form more explosion points on the wedge surface of the combustion chamber, increasing the speed of the detonation wave developing in the combustion chamber. Its working principle is similar to Figure 4 The same as in.

[0054] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. Applicable to oblique detonation engines operating under supersonic wide range conditions, characterized by: The lower surface of the combustion chamber of the oblique detonation engine is set as a wedge surface, and the wedge surface of the combustion chamber adopts a curved surface structure design perpendicular to the flow direction, so that the angle of the wedge surface changes continuously in the direction perpendicular to the flow direction of the combustion chamber inlet.

2. The oblique detonation engine suitable for supersonic wide-range operation as claimed in claim 1, characterized in that: The front edge of the wedge surface of the combustion chamber is in the shape of a straight line, and the rear edge of the wedge surface is in the shape of a curve.

3. The oblique detonation engine suitable for supersonic wide-range operation as claimed in claim 1, characterized in that: The curved surface is a variable wedge angle curved surface.

4. The oblique detonation engine suitable for supersonic wide-range operation as claimed in claim 1, characterized in that: The curved surface takes a cross section perpendicular to the air intake direction, and the contour shape of the cross section is a combination of several smooth curves.

5. The oblique detonation engine suitable for supersonic wide range operation as claimed in claim 3, characterized in that: The variable wedge angle curved surface adopts an n-shaped or / and U-shaped curved surface.

6. The oblique detonation engine suitable for supersonic wide range operation as claimed in claim 4 or 5, characterized in that: The wedge angles at different positions in the combustion chamber perpendicular to the incoming flow direction continuously vary between (θ1, θ2), the value range of θ1 is 15-30 degrees, and the value range of θ2 is 20-40 degrees; wherein θ1 is the minimum wedge angle corresponding to the maximum position of the distance between the wedge surface in the combustion chamber and the upper surface of the combustion chamber; θ2 is the maximum wedge angle corresponding to the minimum position of the distance between the wedge surface in the combustion chamber and the upper surface of the combustion chamber.

7. The oblique detonation engine suitable for supersonic wide range operation as claimed in claim 6, characterized in that: The angle change (θ1, θ2) of the wedge surface is within the fixed range (θ det,CJ ,θ det,max ), where θ det,CJ is the wedge angle corresponding to the Chapman-Jouguet oblique detonation; θ det,max It is the maximum wedge angle corresponding to the condition that the oblique detonation wave does not detach from the body.

8. The oblique detonation engine suitable for supersonic wide-range operation as claimed in claim 1, characterized in that: The wedge angle formed by the curved surface varies in the range of 0-15 degrees.

9. The oblique detonation engine suitable for supersonic wide-range operation as claimed in claim 1, characterized in that: The angle of the oblique detonation wave generated by the combustion chamber varies from 0 to 20 degrees in a direction perpendicular to the wedge surface.

10. The oblique detonation engine suitable for supersonic wide range operation as claimed in claim 1, characterized in that: The Mach number of the inlet flow of the combustion chamber is between 3 and 15.

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